Nano-Kirigami Metasurface with Giant Nonlinear Optical Circular Dichroism

In linear optical regime, it is shown that the polarization, amplitude, and phase of light can be easily controlled by using optical metasurfaces, thus enabling the powerful designs of metalenses, high-efficiency holograms, and so on. In comparison, the manipulation of nonlinear optical processes on the metasurfaces is much more challenging. This is mainly because the metasurface nonlinear source is also modulating the waves emitted from it. Thus, designing nonlinear meta-atoms with multiple optical functionalities is highly desirable. Herein, the broadband and near-unity nonlinear optical circular dichroism (CD) of second harmonic generation from a nano-kirigami plasmonic metasurface is experimentally demonstrated, which is free-standing with total thickness of about one-third of the excitation wavelength. The broadband and near unity nonlinear CD is attributed to both the strong CD of fundamental wavelengths and spin-controlled second harmonic generations from the nano-kirigami meta-atoms with threefold rotational symmetries. The proposed nonlinear nano-kirigami metasurface provides a novel platform for realizing various nonlinear optical functionalities at the nanoscale.